My parents are both left handed. Mum’s handwriting is very classically neat according to a standard form with fairly wide letters. Dad’s is not classically neat, favouring taller letters and shapes more angular than rounded, but it’s definitely tidy and very legible.
Another of the neatest writers that I know is left-handed. (And female. I have observed a moderately strong correlation—though by no means uniform—between classically neat handwriting and being female.) I can think of several other left-handed people that I know, but I don’t know their handwriting. My left-handed grandmother’s handwriting is neat in the fairly illegible cursive style of the era, but she does it with her right hand since they beat left-handedness out of you (in handwriting at least) in those days.
(Fun fact: I and my seven siblings are all “failures”. Consensus seems to be something like 20% chance of a child of two lefties being left handed, so the probability of all eight of us being right handed was somewhere around 17%.)
Is that true? Why would being lefty mean sloppier handwriting? Smudgier maybe because of left-to-right writing system, but sloppier?
Although it’s also possible that RTL writing systems like Perso-Arabic are designed in such a way that it’s ergonomic for the right-handed majority of the population to write in.
It’s an interesting topic, wonder if there are any papers on it
Regardless, 'how people write' has typically been designed by righties. Fascists. Oh how they mock us.
The lefties who try not to push it curl their wrists into that weird lefty-pose. That way does allow them to drag it. I don't do that, thankfully. It looks pretty bizarre, because writing shouldn't require such acrobatics.
I worked in Riyadh for a while. When it came to numbers, since they would generally be writing in Arabic, they'd leave a gap, and then write Western numbers LtoR, before going back to the start of the number and continuing on RtoL in Arabic. That's when it hit me that people who write Arabic push the pencil in the same way that lefties push it in LtoR languages.
Interestingly I didn't see even one adopt the Lefty-hook hand with their right hand. Unfortunately I never noticed anyone there writing Arabic left-handedly. And I watched for it on purpose, because I was genuinely curious about that.
One thing though, is that Arabic letters are formed in a different way than Western letters are. I suppose Western cursive gets close - but cursive is where lefties push the pencil most, and where writing begins to suffer. (Yes, as per other comments, there ARE lefties who can be tidy. But that's like saying there are grandma's out there that can't cook. Of course you can find examples if you look for them.)
Incidentally, I don't do the lefty-hook thing either. But I'm well aware of it since it is part of so many lefty jokes, and I have seen quite a few people who do it.
A much easier solution for left-handers is turning the paper. 45-60 degrees works best for me. Then you don't need to curl your wrist.
The other problem lefties face, that impacts writing clarity, is that when writing in a school binder, those rings are exactly where your wrist needs to be pretty much half the time.
Of course the answer is to write on paper outside the binder, and then turning the paper to a good angle works well enough. But that doesn't help when it comes to coil books, etc, which doesn't impact righties, but does impact lefties.